This article appears to be a dictionary definition.
Sacred history is the parts of the Torah narrative on the boundary of historicity, especially the Moses and Exodus stories which can be argued to have a remote historical nucleus without any positive evidence to the effect.
In a wider sense, the term is used for all of the historical books of the Bible – i.e., Books of Kings, Ezra–Nehemiah and Books of Chronicles – spanning the period of the 10th to 5th centuries BC, and by extension also of the later books such as Maccabees and the books of the New Testament. The term in this sense is used by Thomas Ellwood in Sacred history, or, the historical part of the holy scriptures of the Old and New Testaments, published 1709.
In yet another sense, the term may refer to ecclesiastical history.
Rabbi Neil Gillman, professor of Jewish philosophy at the Jewish Theological Seminary of America, states
“ "I prefer to understand the plagues and the broader narrative of the Exodus from Egypt as redemptive or sacred history. There is a historical kernel to the story, as Tigay notes, but this kernel was elaborated and embellished by generations of Israelites as they told and retold the story from generation to generation, first orally as a folk tale, then later in highly crafted literary documents that even later were conflated into the biblical narrative we read today. The thrust of the entire narrative is our ancestors' conviction that Israel's Exodus from Egypt was part of God's redemptive work, the fulfillment of God's promise to our forefathers.
"Martin Buber puts it this way in his book titled "Moses." It may be impossible to reconstitute the course of the events themselves, he notes, but "it is nevertheless possible to recover much of the manner in which the participating people experienced those events. We become acquainted with the meeting between this people and a vast historical happening that overwhelmed it; we become conscious of the saga-creating ardor with which the people received the tremendous event and transmitted it to a moulding memory."
"Not "the events themselves," then, but "the manner in which the participating people experienced those events" is what we are reading in these Torah portions from the Book of Shemot. And it is this version that continues to have such an impact on us when we recite the story annually at our Passover seders, dipping our fingers into our wine in tribute to the suffering caused by the plagues". The Jewish Week Jan 27, 2006